HIERARCHICAL GARBAGE COLLECTION IN AN OBJECT RELATIONAL DATABASE SYSTEM

摘要

Techniques of hierarchical garbage collection in an object-relational database system are described. When the object-relational database system receives a request to delete an object, the object-relational database system marks the object for deletion. A garbage collection procedure executing in the background can perform iterations of sweep and mark to delete the object and children objects of the object. In each iteration, a layer or “generation” of objects is deleted. The garbage collection procedure can continue the iterations until the object and all descendants of the objects are deleted.

主权项

1. A method comprising:
receiving, by one or more computers, a request to delete a data object, the data object being represented in a record in a data table, wherein an object identifier data field of the record stores a representation of the data object, and a parent identifier data field of the record stores a representation of a parent object of the data object; marking the record for deletion from the data table; and sweeping the data table in one or more iterations, including, in each iteration of sweeping:
deleting, from the data table, each record marked for deletion;deleting each data object represented in an object identifier field of the deleted record; and thenmarking for deletion from the data table each record for which a parent identifier data field stores a representation of the deleted data object, wherein the one or more computers perform the one or more iterations until an exit condition is satisfied.